土建筑遗址干湿耐久性研究

Durability of earthen architecture ruins under cyclic wetting and drying

选择新疆交河故城原状生土试样和重塑土试样进行了干湿循环试验,之后进行了风洞试验和强度试验,研究土建筑的干湿耐久性。试验结果表明,在试样原始含水率比较低的情况下,试样首先经历了一个质量增大的过程,3个干湿循环后,试样的质量变化进入一个相对稳定的范围。随着增湿与脱湿过程中伴随的水分质量的变化,试样质量的整体趋势是减小的。随干湿循环次数增大,原状试样的强度减小,风蚀量增大,即耐久性持续变差。相反,随干湿循环次数增大,重塑样的强度反而增大,风蚀量减小,即耐久性有所提高。重塑样由于重塑过程中其微观结构受到破坏,强度弱化。干湿循环在某种意义上对重塑土起到"陈化作用",愈合损伤的微结构。初期重塑土强度随干湿循环次数的增加逐渐增强,而后强度逐渐衰减抗风蚀能力减弱。

Cyclic wetting-drying were conducted on the undisturbed and remolded specimens from Jiaohe cultural heritage,Xinjiang,China to understand the durability of earthen architecture to wind erosion and the strength attenuation.Test result shows,under the circumstance of the low original water content,the specimens weight is increased during the beginning three wetting-drying cycles,and then proceeds to a relatively steady state.With the change of moisture content during the condensation-evaporation process,specimen weight expressed a decreasing tendency.With the increase in wetting-drying cycles,undisturbed specimens shows a decrease in compressive strength and an increase in wind erosion quantity,reflecting a weakening effect of durability.Comparatively,remolded specimen shows an increase in strength and a decrease in wind erosion quantity,or an inhencing effect of durability at the early wetting-drying cycles;but during the later cycles,a decrease in strength and an increase in wind erosion quantity,or weakening durability is found.It is considered the healing of destroyed microstructure during remolding and the aging of chemical cohesive agents are responsible for the strengthening of remolded specimen at the earlier wetting-drying cycles.